Clean Chemistry Lowers the Cost-to-Treat by Improving Wastewater Treatability and Increasing Capacity: A Case Study on Nanobubble Pretreatment

The Goleta Sanitary District (GSD) Water Resource Recovery Facility (WRRF) in Goleta, California, was experiencing periodic process upsets due to the presence of surfactants in the wastewater. Surfactants are common ingredients in cleaning products and can inhibit the biological treatment process at WWTPs. In 2022, GSD began a full-scale pilot injecting air nanobubbles (NBs) into the wastewater stream prior to the biological treatment process. Nanobubbles are a source of "clean chemistry" that can break down surfactants and other contaminants. The pilot study showed that nanobubble pretreatment resulted in significant benefits, including: a 10% increase in primary clarifier solids removal, a 40% to 54% removal of surfactants, improved process stability and elimination of process upsets, 43% less power drawn from the aeration blowers, recovery of more than 20% capacity in existing infrastructure, significant increase in ammonia removal rates (nitrification), improved settleability in secondary clarifiers, a 44% reduction in chlorine consumption. The results of the pilot study demonstrate the potential of nanobubble pretreatment to improve the performance of WWTPs and reduce the environmental impact of wastewater treatment.